[FIX] web_editor: properly convert img dimensions

Images sometimes shrunk on conversion because of a parenthesis error in
a conditional chain, because dimensions set via element attributes
should be preserved, and because the offset height should be
used rather than the element height as returned by jQuery.

Part-of: odoo/odoo#83233

addons/web_editor/static/src/js/backend/convert_inline.js

@@ -360,9 +360,9 @@ function toInline($editable, cssRules) {
     // fields).
     _.each(['width', 'height'], function (attribute) {
         $editable.find('img').attr(attribute, function () {
-            return $(this)[attribute]();
+            return ($(this).attr(attribute)) || (attribute === 'height' && this.offsetHeight) || $(this)[attribute]();
         }).css(attribute, function () {
-            return $(this).get(0).style[attribute] || attribute === 'width' ? $(this)[attribute]() + 'px' : '';
+            return $(this).attr(attribute);
         });
     });